The present invention relates in general to amplifiers, and, in particular, to improvements in the start-up characteristics of amplifiers, such as audio amplifiers.
Amplifiers exhibit various operating difficulties during certain conditions and at various stages in the operation thereof. In this regard, when the supply voltage is first applied to the amplifier and prior to the time the supply voltage stabilizes, various undesirable operating phenomenon may occur, such as oscillation, resulting in noise being generated in the output of the amplifier. Drastic fluctuation in the supply voltage at the time of first application of power to the amplifier, i.e., at start-up of the circuit, also is capable of producing such undesirable operating conditions.
It has also been found by the inventors that various circuit elements of the amplifier can contribute to the undesirable phenomenon at start-up. In particular, smoothing circuits are subject to unwanted resonant operation in response to ripple or noise components in the supply voltage.